Not applicable.
1. Field of the Invention
This invention relates in general to a spherical roller bearing and, more particularly, to a spherical roller bearing having specialized seals.
2. Description of Related Art
Spherical roller bearings are generally used wherever there is a likelihood that axial misalignment will occur. The internal arrangement of spherical roller bearings allows the inner ring of the bearing to become axially misaligned with the outer ring of the bearing while still maintaining the ability of the bearing to provide reduced rolling friction.
The arrangement of the internal components of a spherical roller bearing presents special problems with regard to sealing the bearing from outside contaminants and for retention of lubricants within the bearing. Most bearing seals use a relatively solid seal member which is firmly attached to either the inner ring or the outer ring of the bearing, with the other edge of the seal in wiping contact with the other race. As such, there is little, if any, ability of such seals to tolerate any axial misalignment because the misalignment of one race with the other will separate the seal material from being in wiping contact with the other race, thus allowing lubricants to leak from the bearing and allowing contaminants to enter into the internal bearing components. The loss of lubricant and the entrance of contaminants into the bearing cause rapid wear and deterioration of the bearing which results in high maintenance and high cost.
One application of spherical roller bearings is in dragline machines used in the mining industry. Dragline machines are a common piece of mining equipment used in strip mines, surface mines, and canal building. Generally, a dragline machine is usually an enormous motorized crane having a boom and cables which drag a scoop across the surface of the ground to dig and gather material for relocation to another place. Once the scoop is filled, the boom of the dragline machine is repositioned by rotating the entire dragline machine on a central shaft. This central shaft and its accompanying pinion shaft, so-called swing shafts, are vertical and is normally lubricated by high grade lubricants. Because the bearings for the dragline shafts are mounted vertically and because the environment of dragline machines usually contains a wide variety of harmful and penetrating contaminants, the use of a traditional labyrinth-type seal allows the bearings for the dragline shafts to loose their lubricants and to allow contaminants to enter the bearing. This bearing contamination and loss of lubricant cause the bearing to wear quickly resulting in frequent replacement of the bearing. Such rapid and unexpected wear can result in catastrophic failures requiring major repairs to the drive train of the dragline excavating equipment that can result in many hours of equipment downtime.
Various designs have been used to prevent this problem. In some cases shield plates have been positioned near the bearings. While shield plates have been partially successful in preventing the entrance of some contaminants into the bearing, these plates fail to retain the lubricants within the vertically positioned bearing and allow the bearing""s lubricants to leak from the bottom of the bearing. This loss of lubricant results in excessive bearing wear and bearing damage. Altogether, there has been no solution to this problem and failures of the dragline shaft bearings have caused a significant amount of cost, labor, and down time to the mining operators due to bearing maintenance and replacement.
The present invention overcomes these and other problems by providing a spherical roller bearing which is capable of allowing misalignment of the inner ring with the outer ring while still providing a seal between the races to keep lubricants within the bearing and contaminants out. Additionally, the present invention provides specially design closure devices which further inhibit the entrance of contaminants into the bearing.
The present invention resides in a spherical roller bearing having the ability to allow for a certain amount of axial misalignment while still maintaining a seal between the inner and outer ring through the use of a uniquely designed seal and through the use of closure plates around the bearing surfaces.
More specifically, the present invention includes uniquely design contact seals which are used on both ends of the bearing. To further enhance the sealing performance of the present invention, closure plates are also used to surround and protect the bearing from outside contaminants.
The present bearing is also a unique design which allows the spherical bearing to be utilized as a packaged bearing which can be installed as a unitized assembly acting as a cartridge-type replacement bearing. The seals, flanges and wear rings of the present invention allow the installer of the bearing to manipulate and install the bearing without damaging the bearing or the components of the bearing during installation. In furtherance of this object, the present invention is also pre-lubed, pre-adjusted, and pre-sealed prior to transportation to the installation point of the bearing. In fact, the present bearing is sealed and lubed for the expected lifetime of the bearing.
Other objects and features of the present invention will be in part apparent and in part pointed out hereinafter.